Banding for ring-shaped coils



Sept. 19, 1933. L. LINDER 1,927,551

BANDING FOR RING SHAPED COILS Filed June 2, 1932 IFLLI'E1 L tn? Lu duzij Lit-1:121"

Patented Sept. 19, 1933.

UNITED STATES PATENT OFFICE BANDING FOR RING-SHAPED COILS Application June 2, 1932. Serial No. 615,064 and in Germany June 5, 1931 Claims.

Bandings of textile fabric, paper or the like are generally used in ring shaped choke coils, loading coils and transformers for insulating the windings from the iron core or from each other. Such 5 bandings are also used as a covering for the wound coil rings to act partly as an electrical and partly as a mechanical protection.

Heretofore it has been usual to employ a band of uniform width for such purposes. It was found, however, that the band overlapped very much more on the inside of the ring than on the outside. This overlapping is detrimental to the underlying banding as the space for further windings on the inside of the ring is considerably reduced. The partly overlapping windings of the band have an unfavorable eiiect if the banding should nowhere be excessively thick due to magnetic effect, such as, for example, the banding between the primary and secondary windings of a ring transformer which are placed one upon another and where it is important to keep the stray capacities as low as possible. In addition, the unequal thickness of the banding is detrimental to the symmetry generally required in ring coils.

In the drawing illustrating the invention, Fig. 1 shows a portion of a band; Fig. 2 the application of the banding to,a ring coil; while Fig. 3 shows an economical manner of cutting a number of bands from a strip.

The above-mentioned defects are, according to the invention, eliminated by using a band of alternately variable width. Fig. l of the drawing illustrates this band 4. The variations in the width of the banding 4 are so arranged that the narrow portions 5 of the band fall on the inside 7 of the ring 8 and the wider parts 6 on the outside as shown in Fig. 2. In this manner it is possible to cover the ring 8 so that the overlapping on the inside equals the overlapping on the outside. If the band portions are to fall into the correct posi tion with great exactitude and if the individual windings are to be placed closely upon each other, it is sometimes of advantage to use a slightly elastic banding material and to make both the narrow portions 5 and wide portions 6 thereof somewhat shorter than required and stretch the band on each turn until the wide or narrow portions thereof are placed in their appropriate positions. In order to facilitate this operation, the

same position as the correctly positioned starting mark.

The wave shaped band 4. may be produced, for example, by cutting a wide band to the desired shape. There need be no waste at such a cutting 69 operation if the material is cut in such a manner that the wide portions 6 fit into the narrow portions 5 of adjacent bands as shown in Fig. 3. It is also possible, of course, to make the waveshaped band 4 directly of suitable raw material.

What is claimed is:

1. A banding for ring-shaped coils character-- ized by a covering band of alternately variable width wound in such a manner over the coil body that the narrow portions of the band are 70 placed on the inside and the wider portions on the outside of the ring.

2. A banding for ring-shaped coils comprising a band having alternate variable widths and wound upon the coil so that the narrow portions of the band lie on the inside of the ring and the wider portions on the outside of the ring, while the connecting portions between the wide and narrow portions of the band he on the sides of the ring.

3. A banding for ring-shaped coils comprising a band having recurring variable widths wound upon the coil so that the edges of the band overlap one another the same amount both on the inside and outside of the ring.

4. A banding for ring-shaped coils comprising a band having alternate narrow and wide portions connected by tapered portions, said band wound upon the coil in a manner so that the narrow portions are on the inside of the ring 9 and the wide portions are on the outside of the ring, while the tapered portions are on both sides of the ring, the adjacent windings of the band overlapping one another the same amount on each turn.

5. A banding for ring-shaped coils comprising a band having alternate narrow and wide por tions wound upon the ring so that the wide portions are on the outside of the ring and the narrow portions are on the inside of the ring, and periodically recurring markings on the band for indicating the correct positions of the portions of the band on the ring.

LUDVVIG LINDER. 

